Whatever length your lens, knowing the habits and personalities of your subjects is an essential in wildlife photography, and I have found that the knowledge I have picked up along the way, has enabled me to make good use of my 70 -300mm lens in this field. I am in Florida, where we have a variety of spectacular water birds. I have learnt that if the osprey leaves the branch upon which she was eating a fish, and flies off, she will inevitably turn and come back down the river, enabling some great in flight shots of bird and prey. I know not to worry that the dragonfly that I was about to capture sunning himself on a reed has departed, as, if I am patient and get set up focusing on the tip of the reed, he will return to that same reed, and I am ready for him. I have learned not to get out of the car for that shot of a hawk on a telegraph pole, as I can invariably get closer in the car than on foot; indeed any kind of transport, be it car, boat or horse makes me less of a threat for some reason. (I have to add that horses are good camouflage but bad tripods). Also, some birds become accustomed to walkers, or canal boats for example, just as deer in large parks are used to cars and hikers, so you have a much better chance of getting within range with them, than in a really wild spot. I could go on at length, but this is just a long-winded way of saying ‘yes’, decide what you want to capture, and then get to know it and it will pay off.